SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7bd505d744b584b56ecb7c20506cb324fe1548fd689f2071c2e63de20840f887' 
  AND token = 'NcPLHOenq/llhlrSMigKhZ5qlAxztJLOnFSxjpCh6TM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}